1. Field of the Invention
The present invention relates to an optical waveguide path coupling structure and a coupling method of an optical waveguide path, an optical waveguide path and its manufacturing method, and an optical device part with the optical waveguide path and its manufacturing method. More particularly, the present invention relates to the optical waveguide path coupling structure and the coupling method of the optical waveguide path, the optical waveguide path and its manufacturing method, and the optical device part with the optical waveguide path and its manufacturing method using a film in which upper and lower surfaces of a core layer are coated with an upper clad layer and a lower clad layer.
The present application claims priority of Japanese Patent Application No. 2000-366411 filed on Nov. 30, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
Optical communication technology utilizing light as a transmission medium of information has been widely used. To execute such optical communication technology, an optical waveguide path coupling structure (an optical module) is used where optical device chips, such as a light-emitting device and a light-receiving device are provided on an optical device substrate and the optical device chips are optically coupled with each other via an optical waveguide path. It is required that information is transmitted in the optical waveguide path suppressing attenuation of light in order to perform such optical transmission.
FIG. 34 is a sectional view showing an example of a conventional optical waveguide path coupling structure. An optical waveguide path coupling structure 100, as shown in FIG. 34, includes: a quarts glass substrate 105 attached with a film 104 in which upper and lower surfaces of a core layer 101 are coated with an upper clad layer 102 and a lower clad layer 103; and an optical device substrate 107 attached with an optical device chip 106 such as a PD (a photo diode) or a VCSEL (a vertical cavity surface emitting laser).
A specular surface 108 having a slope approximately slanting by 45 degrees is formed on one end of the film 104, and light transmitted through the core layer 101 as shown by an arrow from the other end of the film 104 as the optical waveguide path is made to convert its optical path in an vertical direction by the specular surface 108. Then, light vertically converted is converted into a parallel light by a first micro lens 109 arranged on a rear surface of the quarts glass substrate 105 to be emitted toward the optical device chip 106.
On the other hand, a second micro lens 110 is arranged on a position, which opposes to the first micro lens 109 on the optical device chip 106 of the optical waveguide path, via a resin layer 111, and the light emitted from the first micro lens 109 is made incident to the second micro lens 110 and received by the optical device chip (the light-receiving device in this case) 106 via the resin layer 111. On the contrary, when the light-emitting device is used as the optical device chip 106, the light emitted from the light-emitting device is made incident from the second micro lens 110 to the first micro lens 109 and passes the core layer 101 of the film 104 as the optical waveguide path traveling through an opposite route in the foregoing case. Note that both the quarts glass substrate 105 and the optical device substrate 107 are assembled on a base substrate 113 such as a printed substrate via bumps 112.
However, since the conventional optical waveguide path coupling structure 100 requires the micro lenses 109,110 to convert the light passing through the optical waveguide path into the parallel light and the micro lenses 109,110 must be aligned in a predetermined position with high accuracy, there exists a problem that a manufacturing cost increases.
Specifically in FIG. 34, since the micro lens 109 must be arranged in the predetermined position with high accuracy of approximately 1 xcexcm in order to arrange the micro lens 109 on the quarts glass substrate 105, a highly accurate alignment operation is required for arranging the micro lens 109, and thus increase of the manufacturing cost has been inevitable.
In the view of the above, it is an object of the present invention to provide an optical waveguide path coupling structure and a coupling method of an optical waveguide path, the optical waveguide path and its manufacturing method, and an optical device part with the optical waveguide path and its manufacturing method, whereby a highly accurate alignment is unnecessary.
According to a first aspect of the present invention, there is provided an optical waveguide path coupling structure where a first optical waveguide path including a first core layer and a second optical waveguide path including a second core layer are optically coupled, wherein the first optical waveguide path arranged on an optical device chip, which has a first cross section formed such that the first core layer is exposed as an oblique plane with a slight angle at an end portion and a second cross section formed in an approximately vertical direction to the first cross section at a position apart from the first cross section by a predetermined distance, and the second optical waveguide path arranged on a base substrate, which has a first cross section formed such that the second core layer is exposed as an oblique plane with a slight angle at an end portion and a second cross section formed in the approximately vertical direction to the first cross section at a position apart from the first cross section by a predetermined distance, are coupled by aligning the first cross sections and the second cross sections.
According to a second aspect of the present invention, there is provided an optical waveguide path including a film in which upper and lower surfaces of a core layer are multiply coated respectively by an upper clad layer and a lower clad layer, wherein a first cross section with a slight angle to an optical path direction is formed at an end portion side of the core layer on the film to expose the core layer, and a second cross section is formed having a predetermined cross angle with the first cross section.
In the foregoing second aspect, a preferable mode is one wherein the first cross section is a plane approximately perpendicular to a plane of the film.
Also, a preferable mode is one wherein the first cross section is a plane forming a predetermined cross section non-perpendicular to the plane of the film.
Further, according to a third aspect of the present invention, there is provided an optical waveguide path including a film with a lower clad layer, a core layer, a thin film upper clad layer, and a side clad layer having approximately a same height as the core layer, wherein the core layer for alignment used as the pattern for alignment is formed on the film other than the core layer and a first cross section with a slight angle to an optical path direction is formed at an end portion side of the core layer for the alignment to expose the core layer for the alignment, and a second cross section is formed having a predetermined cross angle with the first cross section to expose an end surface of the core layer.
According to a fourth aspect of the present invention, there is provided a manufacturing method of an optical waveguide path using a film in which upper and lower surfaces of a core layer are multiply coated respectively by an upper clad layer and a lower clad layer, the manufacturing method including the steps of: forming a first cross section with a slight angle to an optical path direction at an end portion of the film; measuring a position of the core layer exposed at the first cross section; and forming a second cross section with a predetermined angle from the optical path direction of the film at a position apart from the position of the core layer by a predetermined distance.
According to a fifth aspect of the present invention, there is provided a manufacturing method of an optical waveguide path using a film in which upper and lower surfaces of a core layer are multiply coated respectively by an upper clad layer and a lower clad layer, the manufacturing method including the steps of: forming a metal film pattern on a base substrate; forming the film on the base substrate that includes the metal film pattern; forming a first cross section with a slight angle to an optical path direction of the film by removing a portion of the film on the metal film pattern with ablation processing of an ultraviolet laser; measuring a position of the core layer exposed at the first cross section; and forming a second cross section having a predetermined angle to the first cross section with the laser ablation processing at a position on the metal film pattern apart from the position of the exposed core layer by a predetermined distance.
According to a sixth aspect of the present invention, there is provided a manufacturing method of an optical waveguide path using a film in which upper and lower surfaces of a core layer are multiply coated respectively by an upper clad layer and a lower clad layer, the manufacturing method including the steps of: forming a metal film on a base substrate, adhering the film onto the metal film and removing a desirable portion of the film by an ultraviolet laser ablation processing; removing the metal film under the desirable portion of the film by etching; forming a first cross section at an end portion of a pattern for alignment by the core layer with a slight angle to a direction of the pattern for the alignment; measuring a position of the core layer exposed at the first cross section; and forming a second cross section with a predetermined angle from an optical path direction of the film at a position apart from the position of the exposed core layer by a predetermined distance.
According to a seventh aspect of the present invention, there is provided an optical device part with an optical waveguide path including a film in which upper and lower surfaces of a core layer are multiply coated respectively by an upper clad layer and a lower clad layer, wherein; the film is provided on an optical device chip being a major portion of the optical device part and made to be the specular surface having a slope of approximately 45 degrees on an upper portion of a light-emitting surface or a light-receiving surface of the optical device chip, and a first cross section with a slight angle to an optical path direction is formed at an end portion side of the core layer of the film to expose the core layer.
In the foregoing seventh aspect, a preferable mode is one wherein a hole filled with resin having approximately the same refractive index as that of the core layer is formed from the specular surface having the slope approximately slanting by 45 degrees to the light-emitting surface or the light-receiving surface of the optical device chip.
Also, a preferable mode is one wherein the metal film is formed on the specular surface having the slope approximately slanting by 45 degrees and the resin is coated on the specular surface.
Also, a preferable mode is one, that wherein further includes: a structure in which a spacer is adhered to the optical device chip and the film is formed on the spacer.
Also, a preferable mode is one, that wherein further includes: the structure in which the spacer is formed by a transparent medium and the spacer is protruded from the optical device chip.
Also, a preferable mode is one wherein the first cross section is a plane approximately perpendicular to a plane of the optical device chip.
Also, a preferable mode is one wherein the first cross section is a plane with a predetermined angle non-perpendicular to a plane of the optical device chip.
Also, a preferable mode is one wherein the first cross section with a slight angle to an optical path direction is formed at the end portion side of the core layer of the film to expose the core layer and the second cross section is formed having a predetermined cross angle with the first cross section.
According to an eighth aspect of the present invention, there is provided an optical device part provided with an optical waveguide path including a film with a lower clad layer, a core layer, a thin film upper clad layer, and a side clad layer having approximately a same height as the core layer, wherein the film is provided on an optical device chip being a major portion of the optical device part and made to be a specular surface having a slope of approximately 45 degrees on an upper portion of a light-emitting surface or a light-receiving surface of the optical device chip, and a core layer for alignment used as a pattern for alignment is formed on the film other than the core layer and a first cross section with a slight angle to an optical path direction is formed at an end portion side of the core layer for the alignment to expose the core layer for the alignment, and a second cross section is formed having a predetermined cross angle with the first cross section to expose an end surface of the core layer.
According to a ninth aspect of the present invention, there is provided a manufacturing method of an optical device part with an optical waveguide path, using a film in which upper and lower surfaces of a core layer are multiply coated respectively by an upper clad layer and a lower clad layer, the manufacturing method including the steps of: forming a polymer optical waveguide path on a semiconductor wafer in a process before separating the semiconductor wafer into optical device chips; performing the laser ablation processing to resin of the polymer optical waveguide path with an ultraviolet laser and forming a specular surface with a slope approximately slanting by 45 degrees on an upper portion of a plane being a light-emitting surface or a light-receiving surface of the optical device chip; and forming a cross section with a slight angle to an optical path direction on an other end portion of the polymer optical waveguide path.
In the foregoing ninth aspect, a preferable mode is one wherein the process for forming the polymer optical waveguide path includes the steps of: forming a hole that reaches at least the core layer from the plane being the light-emitting surface or the light-receiving surface on a polymer layer after formation of the polymer layer; and filling the hole with resin of approximately a same refractive index as that of the core layer.
Also, a preferable mode is one wherein the process for forming the specular surface with the slope approximately slanting by 45 degrees includes the steps of: forming a metal film pattern on the upper clad layer of the polymer optical waveguide path; and irradiating the ultraviolet laser in a direction approximately slanting by 45 degrees using a metal film pattern as a mask to perform the laser ablation processing.
According to a tenth aspect of the present invention, there is provided a coupling method of an optical waveguide path that couples a first optical waveguide path including a first film with a lower clad layer, a core layer, a thin film upper clad layer, and a side clad layer having approximately a same height as the core layer, and the second optical waveguide path including a second film with a similar configuration as the first film, wherein the first film is provided on an optical device chip and made to be a specular surface having a slope of approximately 45 degrees on an upper portion of a light-emitting surface or a light-receiving surface of the optical device chip, a first cross section with a slight angle to an optical path direction is formed at an end portion side of each of the core layers to expose the core layer on the first and second films, and a second cross section is formed having a predetermined cross angle with the first cross section, and a height is made to be the same by putting the first cross section and the second cross section of the second optical waveguide path against the first cross section and the second cross section of the first optical waveguide path and by putting surfaces of the first optical waveguide path and the second optical waveguide path against a reference plane common to both the first and the second optical waveguide paths.
According to an eleventh aspect of the present invention, there is provided a coupling method of an optical waveguide path that couples a first optical waveguide path including a first film with a lower clad layer, a core layer, a thin film upper clad layer, and a side clad layer having approximately a same height as the core layer, and a second optical waveguide path including a second film with a similar configuration as the first film, wherein;
the first film is provided on an optical device chip and made to be a specular surface having a slope of approximately 45 degrees on an upper portion of a light-emitting surface or a light-receiving surface of the optical device chip,
core layers for alignment used as a pattern for alignment are formed on positions corresponding with each other on the first film and the second film other than the core layer, a first cross section with a slight angle xcex8 to an optical path direction is formed at an end portion side of each of the core layers for the alignment to expose the core layer for the alignment, and a second cross section is formed having a predetermined cross angle with the first cross section to expose an end surface of the core layer, and
the first cross section and the second cross section of the second optical waveguide path are put against the first cross section and the second cross section of the first optical waveguide path, and the thin film upper clad layer of the first optical waveguide path and the core layer of the second optical waveguide path are made to contact in a thickness direction.
With the above configurations, since the first optical waveguide path arranged on the optical device chip, which has the first cross section formed such that the first core layer is exposed as the oblique plane with the slight angle at the end portion and the second cross section formed in the approximately vertical direction to the first cross section at a position apart from the first cross section by a predetermined distance, and the second optical waveguide path arranged on a base substrate, which has the first cross section formed such that its core layer is exposed as the oblique plane with the slight angle at the end portion and the second cross section formed in the approximately vertical direction to the first cross section at the position apart from the first cross section by a predetermined distance, are coupled by aligning the first cross sections and the second cross sections, the first optical waveguide path and the second optical waveguide path are easily coupled.
Therefore, an optical waveguide path coupling structure of the present invention can be realized without requiring highly accurate alignment.